1. Field of the Invention
The present invention relates to a transmission device, transmission method, information processing device, information processing method, and program, and in particular relates to a transmission device, transmission method, information processing device, information processing method, and program such that, for example, data errors occurrences arising from multipath can be readily prevented.
2. Description of the Related Art
Heretofore, there have been signal processing devices which subject image signals from external devices such as a DVD (Digital Versatile Disc) player or the like to signal processing and supply image signals to a display device such as a CRT (Cathode Ray Tube) or LCD (Liquid Crystal Display).
With such a signal processing device, signal processing is performed, such as noise removal processing to remove noise from the signal of the image supplied from the external device, image conversion processing to convert the image signal so that the image displayed on the display device is of a higher image quality than the image from the external device, image adjusting processing to adjust the brightness or contrast of the image displayed on the display device, and so forth.
FIG. 1 is a block diagram showing a configuration of an example of a current signal processing device. In FIG. 1, a signal processing device 11 is made up of a casing 12, connectors 131 through 134, input selector 14, signal router 15, connectors 161 through 164, connectors 171 through 173, functional blocks 181 through 183, connector 19, remote commander 20, operating unit 21, system control block 22, and control bus 23 and so forth.
With the signal processing device 11, the connectors 131 through 134 are connected to the input selector 14 via signal cables, and the input selector 14 is connected to the signal router 15 via the signal cable. Also, the signal router 15 is connected to the connectors 161 through 164 and the connector 19 via the signal cables, and is further connected to the functional blocks 181 through 183, via the connectors 161 through 164 and connectors 171 through 173. Also, the input selector 14, signal router 15, connectors 161 through 164, and system control block 22 are mutually connected via the control bus 23.
The casing 12 is a metallic casing in a cuboid shape, for example, and the input selector 14, signal router 15, connectors 161 through 164, connectors 171 through 173, functional blocks 181 through 183, system control block 22, and control bus 23 are stored therein.
Also, the connectors 131 through 134, and 19, and the operating unit 21 are provided to the casing 12 so as to protrude externally from the casing.
Cables which connect the signal processing device 11 and external devices (unshown) such as a tuner or DVD player which supplies an image signal to the image processing device 11 are connected to the connectors 131 through 134.
An image signal from an external device is supplied to the input selector 14 via the connectors 131 through 134. The input selector 14 selects an image signal supplied from the connectors 131 through 134, according to control by the system control block 22, and supplies this to the signal router 15.
The signal router 15 supplies the signal supplied from the input selector 14 to the function block 18i, via the connectors 16i and 17i, according to control by the system control block 22 (in FIG. 1, i=1, 2, 3).
Also, the signal subjected to signal processing is supplied to the signal router 15 from the functional block 18i, via the connectors 17i and 16i. The signal router 15 supplies the signal from the functional block 18i to a display device (unshown) connected to the connector 19, via the connector 19.
The connectors 16i and 17i are mutually detachable, and connect each of the signal router 15 and control bus 23, and the functional block 18i. Note that in FIG. 1, four connectors 161 through 164 are provided within the casing 12, and of these, the three connectors 161 through 163 are connected to each of the connectors 171 through 173 of the functional blocks 181 through 183. In FIG. 1, the connector 164 which is not connected to anything can be connected to (a connector of) a new functional block added to the signal processing device 11.
The functional blocks 181 through 183 each have a signal processing circuit to perform signal processing such as noise removing processing, image converting processing, image adjusting processing, or the like. The functional blocks 181 through 183 perform signal processing as to the signal supplied from the signal router 15, and supplies the signal subjected to signal processing to the signal router 15.
The connector 19 is connected to a cable which connects the signal processing device 11 and a display device that displays the image output from the signal processing device 11.
The remote commander 20 has multiple buttons or the like that are operated by a user, and supplies (transmits) an operation signal operated by a user according to user operation to the system control block 22, using infrared rays or the like.
In the same way as with the remote commander 20, the operating unit 21 has multiple buttons or the like that are operated by a user, and supplies (transmits) an operation signal operated by a user according to user operation to the system control block 22.
Upon the operation signal according to user operation being supplied from the remote commander 20 or operating unit 21, the system control block 22 controls the input selector 14, signal router 15, or functional blocks 181 through 183, via the control bus 23, such that processing according to the operating signal thereof is performed.
With the signal processing device 11 thus configured, the image signal is supplied to the signal router 15 via the connectors 131 through 134 and the input selector 14, and the image signal is transferred (transmitted) between the signal router 15 and the functional blocks 181 through 183, via signal cables.
In recent years, the capacity of image signals subjected to signal processing by the signal processing device 11 has tended to be larger in accordance with increases in high definition of images. As the capacity of the image signal increases, for example the image signal is transferred at high speed between the signal router 15 and the functional blocks 181 through 183, via signal cables. Thus, when a signal is transferred at high speed, problems occur in the signal transfer from influences such as frequency features of the signal cable, crosstalk, shifting (skewing) of timing that occurs with parallel signal cables, and so forth.
There is a method to perform signal transmission with wireless communication. The wireless communication here may include proximity non-contact communication used with IC (Integrated Circuit) tags and so forth which uses electromagnetic induction to transfer a signal, for example, or wireless communication which uses radio waves.
In order to perform proximity non-contact communication, the transmission side and receiving side should be disposed in a state of a certain proximity to one another, and accordingly, when proximity non-contact communication is performed between boards on the signal processing device, constraints are received regarding placement of the boards and so forth.
On the other hand, with wireless communication using radio waves, there are no such constraints. For example, Japanese Unexamined Patent Application Publication No. 2003-179821 discloses a signal processing device which performs signal processing by boards housed within the same casing transfers a signal by wireless communication using radio waves.
As described in Japanese Unexamined Patent Application Publication No. 2003-179821, for example by the signal router 15 and the functional blocks 181 through 183 transferring a signal by wireless communication using radio waves, problems which occur by transferring a signal at high speed via a signal cable can be avoided.
However, upon the signal router 15 and the functional blocks 181 through 183 transferring a signal by wireless communication using radio waves within the casing 12 of the signal processing device 11, multiple transfer paths (multipath) with differing transfer path distances occur as a result of the radio waves reflecting off the wall face of the casing 12 or by diffraction of radio waves due to the boards built into the casing 12. Upon multipath occurring, multiple signals having shifted phases arrive at the receiving side that receives the signal, the multiple signals thereof interfere with one another such that multipath fading occurs, and an error occurs in the bit (bit string) reproduced on the receiving side.
That is to say, upon multipath occurring, for example the signal of the bit transmitted later is affected by the signal of the bit transmitted earlier (in the past), and consequently, multipath fading occurs wherein the waveform of the signal of the bit transmitted later is deformed, and an error can occur in the bit reproduced on the receiving side.
Also, the phases of the signals can shift, thereby interference occurring, whereby interference occurs, with multipath occurring with other than wireless communication in a casing, e.g. with mobile communication by a portable telephone whereby the radio waves reflect against structures such as buildings. Further, other than such wireless communication also, for example, in transmitting a signal via a cable, the signal may reflect against the end portions of the cable, whereby interference occurs between the signal to be transferred and the reflected signal.
With general wireless communication, methods to counter multipath from signal processing, for example includes a method that employs OFDM (Orthogonal Frequency Division Multiplexing) for a modulation method, a method that performs RAKE receiving at the receiving side along with employing a specter diffusing method for a modulation method, a method that employs MIMO (Multiple Input Multiple Output) using a multi-antenna (multiple antennae) at the transmitting side and receiving side, and a method using a waveform equalizer and so forth.
However, with the method employing OFDM for the modulation method, the processing load for FFT (Fast Fourier Transform) for modulation and demodulation, or for A/D (Analog/Digital) conversion is heavy, in the case of performing processing at a high speed, heat has to be dealt with.
With the method employing a specter diffusing method for the modulation method and performing RAKE receiving, processing has to be performed at a chip rate several times faster than the baseband speed at the time of modulating or demodulating, whereby realizing high speed communication is difficult.
With a method employing MIMO or a method employing a waveform equalizer, problems may occur such as noise that is uncorrelated with the transferring information can be superimposed on the transferring information, space to dispose the antennae within the casing is limited so disposing of a multi-antenna so as to be mutually uncorrelated is difficult, high speed A/D conversion is performed, inserting a UW (Unique Word) in a packet is performed, and a large-scale predicting circuit is used in order to improve accuracy of predicting changes to transfer features, and so forth.
Also, in order to deal with multipath, there are methods to perform error correcting of bits occurring in the communication path on the receiving side; for example, a method that uses a combination of convolutional coding and Viterbi decoding, or uses error correcting encoding such as RD (Reed-Solomon) encoding and turbo encoding.
However, performing error correcting on the receiving side demands a band communication bandwidth wider by the data amount increased by error correcting encoding, or compressing the data at a higher compression rate.
Also, both the transmission side and reception side end up using larger circuits, in order to generate error correcting encoding on the transmission side, and in order to perform error correcting on the receiving side.